The present invention relates to status reporting units, particularly those units which reliably report status signals from one or more status reporting units. In data processing systems having a plurality of interconnected data processing units such as computers, tape drives, disk files, printers, display units and the like, diagnosis of error status including the detection that an error has occurred becomes a complex problem. The difficulty arises in that the status reporting circuits themselves may have an error condition, thereby blocking report of an error condition in an associated unit. Further, it is desired to control the cost of such units by providing a simple yet effective error tolerant status reporting system, particularly for reliably reporting error conditions.